An Injection Device With Needle Cleaning

Abstract

The invention relates to a medical injection device having a needle cannula for multiple use and which needle cannula is cleaned between subsequent injections. The needle cannula is preferably cleaned at the distal tip in a cleaning assembly having a hollow cleaning chamber with a variable volume. The distal tip of the needle cannula is maintained inside the cleaning chamber between subsequent injections. The cleaning chamber is defined by an inner surface, a distal seal and a proximal seal. In order to increase the volume of the cleaning chamber during filling of the cleaning chamber one of the seals is formed as a movable plunger which is movable in one direction to expand the volume of the cleaning chamber. To release the movable plunger from the inner surface of the hollow cleaning chamber in order to commence the filling of the cleaning chamber, the movable plunger and the inner wall surface of the hollow cleaning chamber are rotatable in relation to each other during filling of the cleaning chamber.

1 . A medical injection device for injection of a liquid drug, comprising:
 a housing structure supporting a cartridge containing the liquid drug,   a needle cannula mounted relatively to the housing structure such that a distal tip extend in a distal direction and a proximal part extend in a proximal direction and connects with the cartridge at least during injection,   a cleaning assembly comprising a chamber part with a hollow cleaning chamber having a variable volume and defined by an inner surface, a distal seal and a proximal seal, wherein   one of the distal seal or proximal seal comprises a movable plunger which is movable in one direction to thereby expand the variable volume of the hollow cleaning chamber and wherein the movable plunger and the inner wall surface of the hollow cleaning chamber are rotatable in relation to other.   
     
     
         2 . A medical injection device for injection of a liquid drug according to  claim 1 , wherein the cleaning assembly is secured to an telescopically movable needle shield. 
     
     
         3 . A medical injection device for injection of a liquid drug according to  claim 2 , wherein the telescopically movable needle shield and the housing structure are rotatable in relation to each other. 
     
     
         4 . A medical injection device for injection of a liquid drug according to  claim 3 , wherein the inner wall of the cleaning assembly rotates together with the telescopically movable needle shield. 
     
     
         5 . A medical injection device for injection of a liquid drug according to  claim 2 , wherein a front element rotationally fixates the cleaning assembly to the telescopically movable needle shield 
     
     
         6 . A medical injection device for injection of a liquid drug according to  claim 1 , wherein the movable plunger is guided to move axially in relation to the housing structure. 
     
     
         7 . A medical injection device for injection of a liquid drug according to  claim 1 , wherein a hub carrying the needle cannula is guided axially in relation to the housing structure. 
     
     
         8 . A medical injection device for injection of a liquid drug according to  claim 7 , wherein the movable plunger is provided with an outwardly pointing protrusion which is guided in a track or groove provided in the hub or in a hub extension connected to the hub. 
     
     
         9 . A medical injection device for injection of a liquid drug according to  claim 1 , wherein one of the cleaning assembly or the movable plunger is provided with a sloped surface engaging the other of the cleaning assembly or the movable plunger to thereby introduce an axially movement upon relative rotation between the cleaning assembly and the movable plunger. 
     
     
         10 . A medical injection device for injection of a liquid drug according to  claim 1 , wherein the cleaning assembly is provided with a stop protrusion for engaging the movable plunger to thereby prevent further axial movement of the movable plunger. 
     
     
         11 . A medical injection device for injection of a liquid drug according to  claim 1 , wherein the cartridge and the cleaning chamber contains the same preservative containing liquid drug. 
     
     
         12 . A medical injection device for injection of a liquid drug according to  claim 11 , wherein the preservative containing liquid drug is transferrable from the cartridge to the cleaning chamber. 
     
     
         13 . A medical injection device for injection of a liquid drug according to  claim 12 , wherein the cartridge is movable in the proximal direction in relation to the housing structure. 
     
     
         14 . A medical injection device for injection of a liquid drug according to  claim 13 , wherein the cartridge is forced in the proximal direction by the hub. 
     
     
         15 . A cleaning assembly for an injection device, comprising;
 a hollow cleaning chamber defined by an inner wall sealed by a distal seal and a proximal seal, wherein,   the distal seal and the proximal seal are pierceable preferably by a needle cannula, and   one of the distal seal or proximal seal is a movable plunger which radially abuts the inner wall and is movable along the inner wall, and   wherein, the movable plunger and the inner wall are rotatable in relation to each other.